Solvent deasphalting of residual oils with wash oil to remove metal contaminants



Sept- 23, 1958 N. P. PEET 2,853,426

SOLVENT DEASPHALTING oF RESIDUAL. OILS WITH,

WASH OIL. T0 REMOVE METAL CONTAMINANTS Filed March 10, 1955 5Sheets-Shea?I 1 /7 DEASPHAUED 0/1. /N PmPA//E' saLur/af/ Sept. 23, 1958N. P. FEET 2,853,426'

SOLVENT DEASPHALTING OF RESIDUAL OILS WITH WASH OIL TO REMOVE METALCONTAMINANTS Filed Ilarch 10, 1955 3 Sheets-Sheet 2 ArroR fr.

SOLVENT DEASPHALTING OF RESIDUAL OILS WITH WASH OIL T REMOVE METAL CON-TAMINANTS Nick P. Peet, Baytown, Tex., assigner, by mesne assignvments,to Esso Research and Engineering Company,

Elizabeth, N. J., a corporation of Delaware Application March 10, 1955,Serial No. 493,371

22 Claims. (Cl. 196-14.46)

y The present -invention is directed to a method of removing metalcontaminants from petroleum fractions. More particularly, the presentinvention is concerned with the deasphalting of residualv petroleumfractions and the removal of metals during said deasphalting operation.In its more specific aspects, the invention is concerned with theremoval of metal contaminants from residual fractions charged to acatalytic cracking operation.

The present invention may be briefly described ,as a method for treatinga petroleum fraction containing a major portion of components boilingabo-ve about 900 F. and which is contaminated by substantial amounts ofmetal contaminants in which the feed stock is introduced into adeasphalting zone and there contacted with liqueiied, normally gaseoushydrocarbon and a fraction, of

catalytic cycle stock as hereinafter defined under condi-- carbons whichmay be used may be mentioned ethane, propane, propylene, butylene,butane, includingV iso and f normal butane and mixtures thereof. Theethanev under some conditions may contain ethylene and be used suit-lably in the present invention. itations inoperating equipment, it ispreferred to Vuse butane, propane, propylene, butylenes or mixturesthereof Because of pressure lim- 1 isy maintained with the catalystbeing.- removed4 from the with a desirable commercial mixture consistingof about 30% butanes and about 70% propane.

The amount of liquefied, normally gaseous hydrocarbon employed as asolvent in the deasphalting operation ofthe present invention is Withinthe range of about 2 to aboutl0 Volumes o-f thesolvent per volume ofAresidual petroleum fraction employed as afeed stock to the deasphaltinglzone. As a specific example, it has been foundthatabout 3.2 volumes ofliquefied, normally gaseous hydrocarbon solvent by volume of residualoil charged .is a desirableV asphalted oil is withdrawn being maintainedat 180 F.

and the bottom of the tower Where the asphalt is introduced with theresidual oil being 160 F. Y

The invention may also be carried out in a plurality of stages in onevesselor in a plurality ofvessels compris.-

ice

Z Y ing a plurality of stages. The separate stages may be conducted witha temperature gradient and pressure gra-l dient between the stages. Forexample, a temperature and pressureof F. and 550 pounds per square inchgauge may be maintained in the top of one vessel where as thetemperature and pressure in a second vessel may b e from about to 180 FQand from about 400 to 500l pounds per square inch gauge. Y.

The vessels comprising the several stages, as desired, may be arrangedeither in the vertical or horizontaljposition or intermediate thereof.For example, one or more vessels may be vertically arranged and one ormore vessels may be horizontally' arranged or arranged at an angle withthe horizontal to allow thel vesselV also to be used as a,

settling zone for separation of asphalt'i'c material.

The present invention is particularly useful in preparing a feed stockfor catalytic crackingv operations and particularly catalytic crackingoperations of. the fluidized solids.,

or powder type. The catalytic cracking operation may be either of theupflow or downfiow type.. yIn, the uptlow loperation the` vaporized.hydrocarbon is contacted with the;

uidized solids in a 4suspension'and the suspension flowed.y

upwardlyk through a reaction zone.` Likewise, inl thesof called upiiowoperation. the catalyst is regenerated by susdisperse phase andreturnedto the dense' phase withthey reaction products liowing outy of thereactor and the cat-y alyst. liowing downwardly therefrom. In` theso-calledl downtiow cracking operation, the catalystl fouled with car'-bonaceous. material and/ or coke is regenerated by suspending it in acombustion supporting gas, such as air, and

owing same into a regeneration zone wherein a'disperse phase and a densephase are maintained, they combustion,`

products being1 led off from thefdisperse phase after' separation of `amajor amount of catalyst therefrom and' the 2,587,554, issued February26, 1954, in the nameof lohn Weikart.

In such' catalytic cracking'op'era'tion's' it has been found` that ifthe charging stock contains' any metal contaminants insignificantamounts, for example,'as little as. l poundof nickel or yless perthousand' barrels of c'harge stock, ther catalytic cracking process'is"advers`ely'affected. In general, other metal components such asvanadium aiidl iron are'undesirableinthesamema'n'ner as is nickel butare less troublesome; 'on a weight basis it may be considered thatvanadium is perhaps 1/stli as troublesome asnickel` and iron is perhaps1/2 as troublesome as nickel. Here-V after `in the specification andclaims where the expression equivalent to" 1l0` 'pound of nickelA perthousand' ba'rrels of oil appears, it is to be understood that' this isintended toenc'ompass'the'metal components' nickel, vanadiumand ironwith' nickel use'd at its' full value, vanadium considered atv 1/sth itsactual Weight value and iron considered at l if's actual weight value. f

In the practice of the present invention wherein. residual PatentedSept. 23, 1958 A description of. such a catalytic cracking operation maybe" found in U. S. 'Patent ing operation such as oneof the fluidizedsolids type as mentioned supra.

This wash oil, as mentioned, is a fraction of a catalytic cycle stockwhich is cut from the cycle stock at a tempera ture above about 900 F.and preferably at a temperature in the range from about 900 F. to about1050 F. This wash oil may have a softening point in the range from about100 to 125 F., a specific gravity inthe range from about 1 to about 1.2with the preferred range from 1.05 to about 1.08, a flash point in therange from about 550 to 650 F. and should remove about 85% of the nickelcontaminants from the residual oil which is contaminated with the metalsdown to about 0.5 part per million of metallic contaminants. y

The wash oil may be secured by fractionally distilling the products froma catalytic cracking operation of the typementioned supra at a cut pointof about 900*to about 1050 F. The wash oil may suitably be obtained alsoby precipitating a portion of the cycle stock'from a catalytic crackingoperation and employing the same either with or without the removal ofthe precipitating agent which may be a liquefied, normally gaseoushydrocarbon.

The wash oil may also be obtained from `the distilled products from acatalytic cracking operation by taking a broad residual fraction fromthe distillation of thecracked products and subjecting it to aclarification operation to remove heavier fractions andresidual-catalyst contained in the products from a catalytic crackingoperation of the fluidized powder type. The clarified 'oil may beemployed as a wash oil after suitable treatment such as by solventprecipitation and/ or distillation. Preferably the wash oil is afraction of catalytic cycle stock which is recovered by distillation. l

The term cycle stock as employed in the present invention and in thesense used here refers to a fraction recovered as a distillateintermediate the heating oil fraction and the residual fractionresulting from distillation of the catalytically cracked products. Theterm fraction of catalytic cycle stock means a fraction which isintermediate the heating oil fraction and he heavier residues remainingafter the distillation of the lighter material from the cracked productfrom the catalytic cracking of hydrocarbons.

A desirable wash oil for use in the present invention V- by wet ash, p.p. m Fe by wet ash, p. p. m

The present invention will be further illustrated ,by reference to thedrawing in which:

Fig. 1 is in the form of a diagrammatic ow sheet illustrating asimplified preferred procedure for carrying out the deasphalting step ofthe present invention;

Fig. 2 illustrates the employment of the present 'inven- Y tion in acatalytic cracking operation and the of the fraction of the catalyticcycle stock; A

Fig. 3 is a diagrammatic ow sheet of a modificationl of Fig. 2;

Fig. 4 is a still further diagrammatic lloW sheet oifan-V other mode ofpracticing the present invention;v

preparation Fig. 5 is a diagrammatic flow sheet of a modified procedurefor carrying out the deasphalting step of the present invention; and

Fig. 6 is a diagrammatic flow sheet of another modified procedure forcarrying out the process of the present invention.

Referring now to the drawing in which identical numerals will beemployed to designate identical parts, in Fig. 1 a deasphalting tower,such as 11, is provided into which a crude residue is introduced atapproximately a central part thereof through line 12 and through aspider or distributing means 13. Propane or other liqueed, normallygaseous hydrocarbon is introduced into the tower'11 by way of line 14 toow countercurrently to the residual fraction introduced by line 12. Awash oil which is a fraction of catalytic cycle stock is introduced intothe upper portion of tower 11 through line 15 and ows downwardly thereinafter being distributed through a spider or distributing means 16.

Deasphalted oil in propane solution is removed from the upper portion ofthe tower 11 by way of line 17 and after stripping of dissolved propanemay be introduced as a feed stock into a catalytic cracking operation.Asphalt is removed from the bottom of the tower by way of line 18 andthis asphalt contains substantially all of the metal* contaminantspresent in the crude residue introduced by line 12. The conditions indeasphalting tower f 11 are those exemplified supra.

In Fig. 2 another mode of operation is performed in which crude oilwhich contains metal contaminants, such as nickel, vanadium, iron, 'andthe like, is introduced into the system by way of line 20 and charged toa fractional distillation zone 21 which may be a plurality of fractionaldistillation towers, each equipped with internal vapor-liquid'contactingmeans, such as bell `cap trays. Zone or tower 21 is provided with aheating means as illustrated by a stream coil 22 for adjustment oftemperaturesand pressures therein. In distillation zone 21 lightfractions including gasoline may be removed by line 23, kerosenefractions by line 24, and heating fractions by line 25 and a gas oilfraction by line 26. Crude residue may be discharged from Zone 21 byline 27 for further processing as will be described.

The gas oil fraction is then charged by line 26 into a catalyticcracking zone 28 of the type illustrated supra wherein catalyticcracking takes place at temperatures, for example, from about 800 toabout ll50 F. The cracked products issue from zone 28 which is shown asa block in the flow diagram by line 29 and introduced thereby into adistillation tower or zone 30 which, like zone Y21, is provided withinternal vapor-liquid contacting means and with a heating meansillustrated by steam coil 31.

In zone 30 conditions of temperature and pressure are adjusted to takeoverhead a light fraction through line 32, gasoline components throughline 33 and heating oil through line 34. A residual fraction includingfinely divided catalyst which may have carried over from zone 28 by line29 is discharged by line 32a. A fraction of catalytic cycle stock cut ata temperature of about 900 to l050 F. is withdrawn from zone 30 by line33a and charged into zone 11 through spider or distributing means 16.

The crude residue withdrawn from zone 21 by line 27 controlled by valve34a is introduced into line 12 deasphalted oil substantially free ofliquefied, normallyv gaseous hydrocarbons is removed from stripper 35 byline 38 and introduced thereby into line 26 for charging in thecatalytic cracking zone 28 in admixture with the hydrocarbons in line 26or alone as may be desired.

It may be desirable not to charge the crude residue fromy zone 21 intozone 11 and under these circumstances the crude residue in line 27 rnaybe withdrawn from the system through line 39 controlled by valve 40 oronly part of the reisdue in line 27 may be charged to line 12. Likewise,other crude residue may be introduced into zone 11 by opening valve 41in line 12 connecting to a source of other crude residue which Iarecontaminated withmetals.

A still further mode of the present invention may be illustrated withrespect to Fig. 3. In this particular mode, the feed stock to catalyticzone 28 is introduced by line 26 and submitted to cracking operationstherein to form a product which is withdrawn by line 29 intodistillation zone 30. In this particular instance, a broader fractionmay be obtained through line 33a than with respect to Fig. 2 by omittingthe side stream Withdrawn by line 34 by closing off line 34 by valve34b. Under these conditions, the fraction rin line 33a may suitably beadmixed with a liquefied, normally gaseous hydrocarbon, such as one ofthe type mentioned before, introduced by line 50 and the admixtureiiowed into a precipitation zone 51 which may be operated similarly todeasphalting zone 11 to obtain a fraction of the catalytic cycle stock,the oil solution of liquefied, normally gaseous hydrocarbon removed fromthe catalytic cycle stock being discharged from zone 51 by line 52 whilethe precipitated material is discharged from zone 51 by line 53 intoline 54 whichv is controlled by valves 55 and 56. By closing valve 55the material from zone 51flows into a stripping zone 57 provided with aheating means 58 for removal of liquefied, normally gaseous hydrocarbonby line 50 for reintroduction into line 33a, the oily material free ofnormally gaseous hydrocarbon then being introduced by line 59 controlledby valve 60 into deasphalting tower-11 through spider 16.

In another mode of the present invention, thematerial from line 53 andline 54 without removal' of normally gaseous hydrocarbon would beflo-wed directly into line 59 by closing valve 56 and'opening valve 55,Under these circumstances, the material introduced into line 59 by wayof line 54 will supply at least part of the liquefied, normally gaseoushydrocarbon which may be supplemented by liquefied, normally gaseoushydrocarbon introduced into tower 11 by line 14 for treatment of cruderesidue introduced yby line 12 through spider 13, the precipitatedasphalt being withdrawn by line 18 and the deasphalted oil free ofmetallic contaminants then being also withdrawn by tower 11 by line 17and introduced into stripper 35 for removal of liquefied, normallygaseous hydrocarbon by way of line 37 and to recover deasphalted oil byline 38 for introduction into line 26. It is to be noted that line 26 isprovided with a valve 26a so as to regulate the amount of extraneousfeed introduced by line 26.

A still further mode of the present invention is illustrated in Fig. 4wherein two catalytic cracking zones are employed. In this mode, acatalytic cracking zone 70 -which may be of the upflow type and acatalytic cracking zone 71 which may be ofthe downow type are employed.Feed stock, such as gas oil, is introduced into zone 70 by way of line72 and submitted to cracking in a fluidized powder operation to form acracked product which is discharged from zone 70 by line 73 andintroduced thereby into a distillation zone 74 which, like zones 30 and21, is provided with suitable internal vapor-liquid contacting means toallow a sharp separation among the products. Heat is supplied foradjustment of temperature and pressure in zone 74 by a heating means,such as steam coil 75. Light fractions are removed from; zone 74 by line76, intermediate boiling' fractions` by lines 77 and 78 and a ratherbroad cycle stock fractonwhich contains catalyst carried over to zone 74byl line 73 is withdrawn by line 79 into a clarier, such as a Dorrthickener 80, wherein a separation is made between the catalyst andheavier fractions and the clarified oil, the heavier fractions beingdischarged from thickener '80y by line 81 while the clarified oil is'Withdrawn by line 82 controlled by valve 84 for further treatment aswill be described.

A feed stock, such as a gas oil, isr introduced into catalytic crackingzone 71 by way of line '85' and` cracked as a suspension to form aproduct which is withdrawn from` zone 71 by line 86, the claricd oil inline 82 being, admixed with the cracked products either in line `86- orin distllation zone 87 into which the claried oi-l and the crackedproducts are introduced. Zone 87 is providedv with suitable internalvapor-liquid contacting means tok make a separation of the lighterproducts from the catalytic cycle stock and to recover thedesirablefractionsY fied oil and cycle-stock from zones 70 and 71 isdischarged from zone 87 by line 91 controlled by valve 92 and introducedthrough spider or distributing means 16 into deasphalting tower or zone11 wherein iticontacts the contaminated crude residue introduced by line12 andspider 13 and propane introduced by line 14 to precipitate as-`phalt containing the metal contaminants which is removed by line 1'8.

The deasphalted oil in propane solution is withdrawn' by line 17 intostripper 35 and the propane removed by-l line 37, the deasphalted oilfree `of propane being withdrawn by line 38 and introduced into line '85for cracking in zone 71.

It is to be understood that the deasphalted oilin line 38 may be chargedto zone 70 or z-one 71 or to both of them as may be desired.

It is to be noted that the clarified oil in 1ine'82 may be routed atleast in part as may ben desired into a precipitation zone such as 51 byopening valve 94 in branch line for recovery of wash oil by line 52 fo-ruse in zone 11;

While the present invention has been described with respect to Fig. 4with the clariiiedA oil from thickener 80 being directed into zone 87,it is understood'thatthe clarified oil from zone 80 and the cycle stockfrom either or both of zones 74 and 37 may be combined and distilled orsubjected to treatment for recovery of a fraction of the cycle stock ina separate distillation zone; or, alternatively, the icycle stocks andclaried oil in admixture may be subjected to a solvent precipitationtreatment as desired either with. or withoutsubsequent distillation.

In Fig. 5, a modied procedure for the deasphalting operation isdescribed. Specifically, Fig. 5` refers to the employment of a pluralityof stages with a temperature and pressure gradient between the stages.In Fig. 5, the tower 11 may comprise a plurality of stages and theincorporator and settler 101 comprise an additional stage; Wash oil ofthe type described .supra and derived from catalytic cycle stock isintroduced into the system by line 102 'which connects into line 103 byway of which the wash oil is introduced into the top of deasphaltingtower or zone 11 by way of spider or distribution means 16. Thedeasphalted oil in propane-butano solution leaves the tower 11 by line17 for. removal of propane-butane and for subsequent use as a catalyticcracking stock. Asdescribed previously, the crude residue is introducedinto tower 11 by line 12 and through spider 13 while propane- -butanesolvent is introduced by line 14, the asphalt containing metalcontaminants being discharged bp line 18.

To increase the removal'of metals a portion ofthe deasphalted oil may berouted into settler 101 by closing valve 104 in line 17 which causes thedeasphalted oil in* propane solution to flow byline 105 throughanorificetypeor other mixing devicev 100 and thence through heat'exchanger or heating means 106 into settler 101 whereby a separation ismade between a lfurther asphalt phase and a deasphalted oil inpropane-butane solution phase which is discharged back into line 17through line 107. The settler 101 allows separation of the asphalt phasewhich is Withdrawn by line 103 and returned to the zone 11 with the washoil.

It is desirable that a portion of the asphaltic phase including Wash oilintroduced by line 102 be admixed with the deasphalted oil inpropane-butane solution in line 105. To this end line 108 controlled byvalve 109 is provided which allows the material in line 103 to bedischarged into line 105 for admixing with the deasphalted oil solution.

It may be desirable to close off valve 109 and introduce wash oildirectly into line 108 and into line 105 and this may be accomplished byclosing valve 110 or throttling same and bypassing at least a portion ofthe wash oil from line 102 by line 111 into line 108 as may be desired.

In operations according to Fig. 5, a temperature of 150 F. and 550pounds per square inch gauge may bc maintained in the top of tower 11,whereas the mixture introduced in settler 101 may be at a pressure of450 pounds per square inch gauge and and at a temperature of 170 F. Thisis accomplished by passing the mixture through the heat exchanger 106and by suitable adjustment of controls. By providing a pressuredifferential of 50 to 70 pounds per square inch gauge across theincorporator 100 or other mixing device, complete mixing is obtained. Byproviding a small temperature rise after mixing, the asphalt willprecipitate more readily on the wash oil droplets increasing theirV sizeand permitting adequate settling in settler 101. The mixture ofprecipitated asphalt from settler 101 may be pumped as shown to thetower 11 which improves distribution due to the larger'volume of thematerial recycled. By main-v taining a to 20 F. temperature gradientacross the -top of the tower 11, the deasphalted oil yield is adjustedto a desired level ahead of the stage comprising mixer 100 and settler101 which reduces the amount of nickel or other metal contaminants to beremoved from the deasphalted oil. This operation also serves to decreasethe amount of wash oil which might be carried over into the deasphaltedoil solution.

In Fig. 6 a further modifi-cation of the present invention is shown. Inaccordance with this modification there is provided a suitabledistillation zone 120, such as a so-called vacuum still zone which isoperated kat pressures of about 25 mm. to 250 mm. of mercury. Ametals-contaminated petroleum feed stock fraction containing a majorportion of components boiling above about 900 F. is introduced into thedistillation zone 120 by line 121, the feed stock being heated at asuitable temperature such that the lighter portions thereof are ilashedolf under Ithe pressure conditions given and ascend the zone 120 invapor form for withdrawal through an upper discharge line 122. Theheavier portions of the feed stock descend to the bottom of the zone 120for withdrawal through a lower discharge line 123. It will be understoodthat, if desired, the zone 120 may be lprovided with one or more sidedischarge lines (not shown). A suitable wash oil of the type describedabove is charged to the distillation zone 120 by line 124. The wash oilcontacts the feed stock in zone 120 and atects a substantial removal ofmetal contaminants from the vaporized lighter components of the feedstock.

The vaporized lighter components of the feed stock withdrawn by the line122 are then passed through a suitable cooler 12S for liquefaction andthence to a tower deasphalting zone 126 through a suitable distributingmeans 127. Propane or other liquefied, normally gaseous hydrocarbon isintroduced tothe tower 126 by way of a line 128 to ow countercurrentlyto the 'feed stock fraction.

Deasphalted oil in solution is removed from theV upper portion of thetower 126 by way of a line 129 and after being stripped of normallygaseous hydrocarbon may be introduced as a feed stock into a catalyticcracking operation. Asphaltic components are Withdrawn through thebottom of the tower 126 through a line 130.

If desired, and sometimes preferably, a still further reduction of metalcontaminants may be obtained `by charging a suitable wash oil of thetype described above to the deasphalting tower through a distributingmeans 131 fed by a line 132 controlled by a valve 133. The conditions inthe deasphalting tower 126 are those exemplied supra.

It is to be emphasized that in lconducting operations in accordance withthe procedure exemplified by Fig. 6

the Wash oil should not be brought into contact with the crude residueto be decontaminated in the distillation zone while such residue is inliquid form for in this situation the wash oil may become dissolved inthe crude residue and metal contaminants-removal may not be effected.

In general, it may be stated that the wash oil should be brought intocontact with the metals-contaminated crude residue while such cruderesidue is in a nonsolubilizing ycondition with respect to the wash oil(i. e. catalytic cycle stock). This may be accomplished, for example, byadding the wash oil to the crude residue in the presence of a liquid,normally gaseous hydrocarbon (Figs. 1-5) or by adding the wash oil tovaporized crude residue or to a vaporized lighter portion thereof (Fig.6).

From the foregoing description of the several modes of practice of theinvention, it is clear that the invention maybe practiced in severalWays and the fraction of the catalytic cycle stock may be obtained vbyany one of several ways from the cracked products. The fraction may beobtained by distillation, solvent precipitation, precipitation bymechanical means with subsequent distillation and/or solventprecipitation or by other reducing operations which will removefractions boiling below 900 F.

In order to illustrate the invention further, runs were made comparingthe deasphalting of crude residue from West Texas crude withoutemploying a wash oil and while employing a fraction of catalytic cyclestock as a Wash oil. The operations are presented in Table II:

Table Il Fraction of Fraction of Wash Oil Used None Catalytic NoneCatalytic Cycle Cycle Stock Stock Vol. Percent Wash (Based on Residue)None 17. 2 None 17. 0 Actual DAO Yield Vol. Percent 47. 5 49. 9 60. 467. 2

DAO Inspections:

Sp. Gr. (S0/60 F 0.9459 0. 9190 0.9578 0.9683 Con. Carbon, Wt. Percent3. 77 3.00 5. 27 5. 41 Agg. Ash, p. p. m 6.8 5.9 16.8 12.0 Ni Cont., p.p. m.. 1.6 0.19 3. 04 0.75 V Cont., p. p. m 2.12 0.26 4. 52 0.89 FeCont., p. p. m 1.17 1. 67 Percent Ni Reduction. 88. 1 75. 3

It will be seen that 88% and 75% nickel reductions were obtained,respectively, at deasphalted yields of approximately 50% and 67% withsubstantially all of the nickel, which is the contaminant having themajor effect, being removed.

The crude residue employed as a feed stock of the present invention isthe residue obtained as exemplitied by distilling crude oil to `removethe valuable components thereof. The crude oil and its residues byvirtue of being in contact with earth formations, processing equipment,tanks, pipe lines, and the like, will contain various metals, such lasnickel, vanadium, iron and numerous others too numerous to mention here,which deleteriously affect the catalytic activity of the catalyst incatalytic cracking operations. Since the metal contaminants eventuallyend up vin the crude residue, it `is desirable, as illustrated in thepractice of the present invention, to remove the metal contaminants fromthe desirable fractions of the crude residue before using same incatalytic cracking operations. Other .metal-containing compounds such asthe naturally occurring porphyrins of nickel, vanadium, iron, and thelike are present as contaminants in crude petroleum and its residues andmay be removed in accordance with this' invention. The presentinvention, therefore, has great utility in allowing valuable componentsof crude residue to be catalytically cracked which heretofore could notbe cracked sufficiently to obtain maximum yields of desired productswithout formation of undesirable products, such as gas and coke.

As illustrative of crude residues suitable for treatment in the practiceof the pres'ent invention and for recovery of fractions rsuitable forcatalytic cracking, the following inspections are presented in TableIII.

Table IIL-Feed inspections 18.9% West Texas residuum From theinspections of a typical crude residue, it will be seen that thisparticular residuum is contaminated with relatively large quantities ofnickel, vanadium, and

' iron which deleteriously affect the catalytic cracking operation.

The present invention has wide utility and is being used commercially inremoving anywhere from about 50% to 75% or more of the nickel fromapproximately 25,000 barrels of crude residue being charged to adeasphalting tower in which about 1600 barrels per day of a fraction ofthe catalytic cycle stock obtained by distilling a mixture of clarifiedoil and a fraction of the catalytically cracked products at a cut pointof 900 to 1050 F. The procedure removes the metal contami nants down toabout 0.5 part per million. The efficiency of removal of nickel andother metals and compounds thereof may be increased still further byincreasing the number of stages in the deasphalting tower.

The nature and objects of the present invention having been completelydescribed and illustrated, what I vWish to claim as new and useful andto secure by Letters Patent is:

1. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprisescountercurrently contacting said feed stock in a deasphalting zone witha liquefied normally gaseous hydrocarbon in simultaneous countercurrentcontact with a separately introduced fraction of catalytic cycle stockunder conditions to form a deasphalted oil phase substantially free frommetal contaminants and an asphalt phase containing substantially all ofthe metal contaminants of the feed stock and separately withdrawing saidphases, said fraction of catalytic cycle stock having a specific gravitywithin the range of about 1.05 to 1.2.

2. A method in accordance with claim 1 in which the fraction of thecatalytic cycle stock is obtained by distillation.

3. A method in accordance with claim l in which the fraction of thecatalytic cycle stock is obtained by deasphalting 4. A method inaccordance with claim 1 in which the fraction of the catalytic cyclestock is obtained by a clarification and distillation operation.

5. A method in yaccord-ance with claim 1 in which the petroleum fractioncontains as little as the equivalent of 1 pound of nickel metalcontaminant per thousand barrels.

6. A method for treating a crude petroleum residue containing `a majorportion of components boiling above 900 F. Iand contaminated with metalcontaminants which comprises deasphalting said residue inycountercurrent con- -tact with a liquefied normally gaseous hydrocarbonin a deasphalting zone while simultaneously countercurrently contactingsaid residue with a separately introduced fraction of catalytic cyclestock under conditions to form a deasphalted oil phase and an asphaltphase, and recovering said deasphalted oil phase, said Icatalytic cyclestock being obtained by catalytic cracking of la gas oil fraction ofcrude petroleum .and said deasphalted oil phase, said fraction ofcatalytic cycle stock having a specific gravity within the range ofabout 1.05 to about 1.2.

7. A method in accord-ance with claim `6 in which the lfraction of thecatalytic cycle stock is obtained by distillation.

8. A method in accordance with claim 6 in which the fraction of thecatalytic cycle stock is obtained by detasphalting.

9. A method in accordance with claim 6 in which the fraction of thecatalytic cycle stock is obtained by a clarification and distillationoperation.

10. A method in accordance with claim `6 in which the petroleum fractioncontains as little as the equivalent of 1 pound of nickel metalcontaminant per thousand barrels.

11. A method in accordance with claim 6 in which the crude petroleumresidue is obtained from the crude petroleum from which the gas oilfraction is obtained.

12. A method for treating a Ipetroleum fraction feed stock containing `amajor portion of components boiling yabove 900 F. and contaminated by asubstantial amount of metal contaminants which comprises introducingsaid Afeed stock into a deasphaltng zone comprising a plurality ofstages and there countercurrently contacting said feed stock with aliquefied normally gaseous hydrocarbon in simultaneous countercurrentcontact with a separately introduced fraction of catalytic cycle stockunder conditions -to form a deasphalted oil phase substantially freefrom metal contaminants Vand an asphalt phase containing substantiallyall of the :metal contaminants of the feed stock and separatelywithdrawing said phases, said conditions encompassing a temperaturegradient between said stages with the -highest temperature at the stageadjacent the point of withdrawal of said deasphalted oil phase, saidlfraction of catalytic cycle stock having a specific gravity within therange from about 1.05 to 'about 1.2.

13. A method 4for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of :metal contaminants which comp-rises vapo-rizingat least a portion `of said feed stock, countercurrently contacting saidvapors with a fraction of catalytic cycle stock .to substantiallyextract metal contaminants from said vapors, collecting and liquefyingthe thus contacted vapors, deasphalting the thus vcollected liquid -bycountercurrently contacting the same with a liquefied normally gaseoushydrocarbon under conditions to for-m a deasphalted oil phase and anasphalt phase and recovering the deasphalted oil phase, said 4fractionof catalytic cycle stock having a specific gravity within the range ofabout 1.05 to about 1.2. A

14. A method for treating a lpetroleum fraction feed stock containing amajor portion Iof components boiling r r 1 l l above 900 F. andcontaminated by a substantial amount of metal contaminants whichcomprises vaporizing at least a portion of said feed stock,countercurrently contacting said vapors with a fraction of catalyticcycle stock to substantially extract metal contaminants from saidvapors, collecting and liquefying the thus contacted vapors,deasphalting the thus collected liquid by countercurrently contactingthe same with a liquefied normally' gaseous hydrocarbon and a -furtherquantity of said catalytic cycle stock under conditions to form adeasphalting oil phase and an asphalt phase, and recovering thedeasphalted oil phase, said fraction of catalytic cycle stock having aspecific gravity within the range of about 1.05 to about 1.2.

15. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprises introducingsaid feed stock into a deasphalting zone and there countercurrentlycontacting said feed stock with about 2 to l volumes per volume of feedstock of a liquefied normally gaseous hydrocarbon and alsosimultaneously countercurrently contacting said feed stock in saiddeasphalting zone with a separately introduced fraction of catalyticcycle stock under conditions to form a deasphalted oil phasesubstantially free from metal contaminants and an asphalt phasecontaining substantially all of the metal contaminants of the feed stockand separately withdrawing said phases, said fraction of catalytic cyclestock having a specific gravity within the range of about 1.05 to about1.2.

16. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprises introducingsaid feed stock into a deasphalting zone and there countercurrentlycontacting said feed stock with about 2 to l0 volumes per volume of feedstock of a liquefied normally gaseous hydrocarbon and alsosimultaneously countercurrently contacting said feed stock in saiddeasphalting zone with a separately introduced fraction of catalyticcycle stock under conditions to form a deasphalted oil phasesubstantially free from metal contaminants and an asphalt phasecontaining substantially all of the metal contaminants of the feed stockand separately withdrawing feed phases, said catalytic cycle stock beingobtained by catalytic cracking of a mixture of a gas oil fraction ofcrude petroleum and said deasphalted oil phase, said fraction ofcatalytic cycle stock having a specific gravity within the range ofabout 1.05 to about 1.2.

17. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprises introducingsaid feed stock into a deasphalting zone comprising a plurality ofstages and there countercurrently contacting-said feed stock with about2 to 10 volumes per volume of feed stock of a liquefied normally gaseoushydrocarbon and also simultaneously countercurrently contacting saidfeed stock in said deasphalting zone with a separately introducedfraction of catalytic cycle stock under conditions to form a deasphaltedoil phase substantially free from metal contaminants and an asphaltphase containing substantially all of the metal contaminants of the feedstock and separately withdrawing said phases, said conditionsencompassing a temperature gradient between said stages, with thehighest temperature at the stage adjacent the point of withdrawal ofsaid deasphalted oil phase, said fraction of catalytic cycle stockhaving a sepcilic gravity within the range from about 1.05 to about 1.2.

18. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprises vaporizing atleast a portion of said feed stock, countercurrently con" tacting saidvapors with a fraction of catalytic cycle stock to substantially extractmetal contaminants from said vapors,v collecting and liquefying the thuscontacted vapors, deasphalting the thus collected liquid by contactingthe same with about 2 to l0 volumes per volume of collected liquid of aliquefied normally gaseous hydrocarbon under conditions to form adeasphalted oil phase andan asphalt phase and recovering the deasphaltedoil phase, said fraction of catalytic cycle stock having a specificgravity within the range of about 1.05 to about 1.2.

19. A method for treating a petroleum fraction 'feed stock containing amajor portion of components boiling above 900 F. and contaminated by asubstantial amount of metal contaminants which comprises Vaporizing atleast a portion of said feed stock, countercurrently contacting saidvapors with a fraction of catalytic cycle stock to substantially extractmetal contaminants from said vapors, collecting and liquefying the thuscontacted vapors, deasphalting the thus collected liquid bycountercurrently contacting the same in a deasphalting zone with about 2to 10 volumes per volume of collect-ed liquid ofY fraction of catalyticcycle stock having a specific gravityy within the range of about 1.05 toabout 1.2.

20. A continuous method for treating a metals contaminated petroleumfraction feed stock containing la major portion of components boilingabove 900 F. in

a deasphalting tower which comprises the steps of continuouslyintroducing a liquefied normally gaseous hydrocarbon into said toweradjacent the lower end thereof, continuously introducing said feed stockinto said tower above the point of introduction `of said liquefiedhydrocarbon, continuously introducing into said tower -above the pointof introduction of said feed stock a primary asphaltic wash material,said primary wash material hav- .ing been obtained by continuouslywithdrawing a first solution of deasphalted oil in said liquefiedhydrocarbon from the top of said deasphalting tower, continuously addinga wash oil to at least a portion of said first solution and intimatelymixing said wash oil with said portion of said first solution in amixing zone to provide a second solution, lcontinuously resolving saidsecond solution into an asphalt phase and a solution of deasphalted loilin said liquefied hydrocarbon in a settling zone and continuouslyrecycling said asphalt phase from said settling zone to saiddeasphalting tower as said primary Wash material, withdrawing an asphaltphase from the bottom of said deasphalting tower and recovering asolution of deasphalted oil in said liquefied hydrocarbon from saidsettling zone, said wash oil consisting of a fraction of catalytic cyclestock having a specific gravity within the range of about 1.05 to about1.08.

2l. A method as in claim 20 wherein said deasphalting tower is operatedto provide for a pressure of about 450 p. s. i. g. and a temperature ofabout F. at the top thereof, and wherein a pressure differential withinthe range of about 50 to 70 p. s. i. g. is maintained across said mixingzone, with the lower pressure being at the outlet end of said mixingzone.

22. A method for treating a petroleum fraction feed stock containing amajor portion of components boiling above 900 F., and contaminated by asubstantial amount of metal contaminants which comprises contacting saidfeed stock in a deasphalting zone with a liquefied normally gaseoushydrocarbon solvent under conditions to form an asphalt phase and asolution of deasphalted oil in said solvent, contacting said solution ofdeasphalted -0il with a fraction of catalytic cycle stock and recovering13 a deasphalted oil substantially free from metal contaminants fromsaid solution, said fraction of catalytic cycle stock having a specificgravity within the range of about 1.05 to 1.2.

References Cited inthe file of this patent UNITED STATES PATENTS1,978,361 Beiswenger Oct. 23, 1934 14 Lindeke et a1. Sept. 8, 1936Jewellv June 29, 1943 Knox Ian. 25, 1955 Hennig Dec. 20, 1955 Webber May21, 1957 Corneil et al May 21, 1957

1. A METHOD FOR TREATING A PETROLEUM FRACTION FEED STOCK CONTAINING AMAJOR PORTION OF COMPONENTS BOILING ABOVE 900*F. AND CONTAMINATED BY ASUBSTANTIAL AMOUNT OF METAL CONTAMINANTS WHICH COMPRISESCOUNTERCURRENTLY CONTACTING SAID FEED STOCK IN A DEASPHALTING ZONE WITHA LIQUEFIED NORMALLY GASEOUS HYDROCARBON IN SIMULTANEOUS COUNTERCURRENTCONTACT WITH A SEPARATELY INTRODUCED FRACTION OF CATALYST CYCLE STOCKUNDER CONDITIONS TO FORM AA DEASPHALTED OIL PHASE SUBSTANTIALLY FREEFROM METAL CONTAMINANTS AND AN ASPHALT PHASE CONTAINING SUBSTANTIALLYALL OF THE METAL CONTAMINANTS OF THE FEED STOCK AND SEPARATELYWITHDRAWING SAID PHASES, SAID FRACTION OF CATALYTIC CYCLE STOCK HAVING ASPECIFIC GRAVITY WITHIN THE RANGE OF ABOUT 1.05 TO 1.2.